1. Field of the Invention
The present invention relates to a nitride semiconductor light-emitting device, and more specifically, to a nitride semiconductor light-emitting device with improved light extraction efficiency.
2. Description of the Related Art
Nitride semiconductor light-emitting devices attract the interests, for example, as an illumination light source, and an excitation light source for white light-emitting diode. A nitride semiconductor light-emitting device generally has a structure of sandwiching a light-emitting layer between an n-type nitride semiconductor layer and a p-type nitride semiconductor layer, and luminescence occurs as a result of re-coupling between an electron and a hole.
FIG. 9 is a schematic section view of a conventional nitride semiconductor light-emitting device described in Japanese Patent Laying-Open No. 2006-135311. In the nitride semiconductor light-emitting device shown in FIG. 9, a laminate consisting of nitride semiconductor layers is formed on a substrate 901. The laminate includes, from the side of the substrate 901, a first n-type nitride semiconductor layer 902, an active layer 903, a p-type nitride semiconductor layer 904, and a second n-type nitride semiconductor layer 905 in this order. The second n-type nitride semiconductor layer 905 is formed with a p-side electrode 906 for injecting holes into the p-type nitride semiconductor layer 904, and the first n-type nitride semiconductor layer 902 is formed with an n-side electrode 907.
Here, as the p-side electrode 906, for example, metal such as Al is used, however, when metal is used as the p-side electrode material, the resultant opaque electrode will absorb light to lead the problem of deterioration in light extraction efficiency.